The rapid spread of wireless devices as typified by mobile phones has promoted the use of switching devices. For example, mobile terminals for high frequency communications use a high frequency switch to select multiple high-frequency signals. The switches include mechanical switches and switches using a semiconductor transistor.
Japanese Patent Application Publication No. 2006-109084 (Patent Document 1) and U.S. Pat. No. 7,848,712 (Patent Document 2) disclose providing an inductor between input-output terminals to improve isolation characteristics between the input-output terminals of the switch.
The techniques of Patent Documents 1 and 2 can cancel out parasitic capacitance between the input-output terminals by a reactance component of the inductor and improve the isolation characteristics. However, a parasitic capacitance value between the input-output terminals is small, and thus the inductance of the inductor is made to be high. This makes downsizing difficult.